Abstract
Foam fractionation is a, method of separating components of a solution that differ in surface activity; in such a solution, surface active material concentrates at the liquid surface. When the solution is foamed, a very large additional surface is created in the foam in which the surface active material is therefore concentrated. Proteins are well known as foam stabilisers and foam fractionation has been used to separate enzymes on a laboratory scale. While the process has the potential for protein separation on a large scale, no satisfactory treatment exists that will give a quantitative prediction of the behaviour of a foaming system. The aim of this work was to develop an universal design equation capable of predicting the Enrichment ratio (the chosen criterion of separation efficacy) under any given set of operating conditions. Foam fractionation of an idealised pure protein system of Bovine Serum Albumen in buffer at pH 4.6 was carried out in the batch mode; the range of liquid volume employed being 0.2-11.5 litres. Firstly the operating parameters affecting Enrichment were identified by carrying out experiments over a wide range of operating conditions. The parameters were found to be bulk liquid concentration, foam column height, superficial gas velocity, foaming cell diameter and also bulk liquid depth. Using the concept of Ideal Foam a simplistic Theoretical treatment was developed to give a design equation which has four empirical constants, [mathematical equation] This equation predicts all the experimental results in the region where the assumption of Ideal Foam is valid, with the highest confidence limits using the chi[2] statistical test. The equation does not take into account any change in bulk liquid depth,while the mean foam bubble diameter was found to be essentially constant over the wide range for which the design equation applies. The model has not been adapted for use with binary protein solutions.